Indicator means for ignition systems and the like



INDICATOR MEANS FOR IGNITIOIT! SYSTEMS AND THE LIKE Filed Hay 25. 1929 4 Sheets-Sheet 1 *.lui-lllllll May 2, 1933. H, C, HEAT@ 1,907,069

INDICATOR MEANS FOR IGNITION SYSTEMS AND THE; LIKE.

Filed lay 25. 1929 4 Sheets-Sheet 2 7 N MA 64 ,f// N 7.3"76 l EN] 64- f @Y 5 MMIII. l

May 2; 1933- H. c. HEAToN 1,907,069

INDICATOR MEANS FOR IGNITION SYSTEMS AND THE LIKE Filed Ilay 25, 1929 4 Sheets-Sheet 3 H. c. HEATON 1,907,069

INDICATOR MEANS FOR IGNITION SYSTEMS AND THE LIKE May 2, 1933.

Filed lay 25. 1929 4 Sheets-Sheet 4 17g iff Patented May 2, 1933 UNITED STATES4 HERMAN C. HEATON, OF CHICAGO, ILLINOIS INDICATOR MEANS FOB. IGNITION SYSTEMS THE LIKE Application led Hay '25,

This invention relates to indicator means for ignition systems and the like and more particularly to indicator means for indicating the condition of the ignition systems ,5 of internal combustion engines.

While the invention is particularly adapted for lindicating the condition of the ignition systems for internal combustion engines, the invention is applicable broadly for determining the condition of any electric path or any condition reflected by a change in condition in anelectric path or for measuring the resistance of `an electric path and the appended claims are, therefore, intended to be interpreted accordingly.

In my prior Patent, No. 1,605,724,.granted November 2, 1926,11 have provided an ignition system distributor and indicator in which the desired indication is conveyed by a jump spark action.

In my copending applications, Serial No. 333,805, filed January 21, 1929, and Serial No. 365,934, iled May 25, 1929, I have provided a spark plug testing and condition ascertainingmethod and' means and a high potential insulation or leakage testing method and means.

I have conceived the use of a Neon, or other gaseous tube, for use in making the desired test or measurement, or for indicating the desired condition. It is'well understood that the particular gases in tubes of this sort vary widely and by the term gaseous tube, as used herein, I intend to include any equivalent gaseous tube, regardless of the particular gas employed. For example, Neon is now commonly used where a red light is desired, argon and mercury vapor, or the like, for a green light, and argon and some other chemical in Neon gas, for a blue light. ll find that a gaseous tube of this sort is extremely sensitive and requires but a very slight actuating current. l also find that the slightest di'erences in current or irregularity of current passed through such a tube will show up at once in the tube and that there is a point where the tube lights or ceases to light. The laggirfg factor is negligible and these characteristics are all admirably adapted for the 1929. Serial N0. 365,935.

purposes of the present invention. There is no afterglow, as compared with that in an incandescent filament lamp, and this ,is fur-4 ther important in providing a sharp demarcation between indications where the same tube is used for successively conveying different indications as successively the indications of the condition of the different spark plugs of a multi-plug engine, or successively the condition of the circuit connections to the d'iiferent plugs.

The primary object of the present invention is to obtain an improved indication and more particularly an indication which is extremely sensitive and in which the slightest differences in current will show up at once. vAnother Objectis the provision of an indication requiring a very slight actuating current and with which there is a relative] distinct point where the indication is e 70 fected, also an indication in which the lagging factor or afterglow is negligible. Another object is the provision of generally improved, simpliiied, and relatively inexpensive means for ada ting the indicator for 'the purposes intendiad and particularl a visible indicator system that can be readily installed. Another object is the provision of an indicatorsystem having a low initial installation and maintenance cost, as well as an indicator system having an attractive appearance and which will not interfere with the normal functioning of the motor, but, in fact, promotes maintenance of the motor in a high state of eiciency.

Other objects and advantages of the invention will appear from the following detailed description, taken in connection with the accompanying drawings, in which:

Figure 1 is a schematic circuit diagram, 90 showing an embodiment of the invention;

Fi ure 2 is a side elevational view of the distributing arm and rotatable post of Figure 1;

Figure 3 is a fragmentary schematic cir- 95 cuit diagram, showing another embodiment of the invention;

Figure 4 is a vertical sectional view, showing another embodiment and taken axially through the distributor cover;

Figure A5 is a horizontal section, taken on the line 5-5 ofA Figure 4;

Figure 6 is a side lelevational view o'f the slght sleeve of Figure 4;

Figure 7 is a side elevational view of the internal gaseous tube supporting sleeve `the evice shown in the invention;

of Figure 4;

Figure 8 is a vertical section through the internal gaseous tube supporting sleeve, taken on the line 8-8. of Figure? Fi ure 9 is a view similar to Figure 4, showing another embodiment of the invention;

Figure tributor cap shown in Figure 9;

Figure 11 is a fragmentary detail view, partlally in section and showing the manner of angularly or positionally directing the light indication in the embodiment of Figures9and 10;

Fi e 12 is amore or less dia ammatic and agmentary view, partially 1n section, showing another'embodiment of the invention; L l

Fi ure 13 is a 10 is a top plan view of the disront elevational view of e 12e; A L -Figure 14 is a side evational view of a spark plug with another embodiment of the inventlon applied thereto.;

Fi ure15 is a more or less di ammatic and i ustrative section, simllar to igures 4 and 9 and showing another embodiment of Fi re `16 is a view. of a gaseous, tube showmg in elevation', and more or lessfgdiaammatically, another embodiment ofthe mvention; and

Figures 17 and 18 are more or less diagrammatic views of two further embodil lments of the invention.

Referring, first, to the diagram of Figure 1, the particular circuit therein illustrated includes a spark coil 5, having a pri- .mary winding 6, which is intermittently Vconnectedto a source of low potential current by means of an interrupter 8 and a secondary winding 9, which forms a source p ofv high potential ignition. current for the spark plugs 10.

The igmtion current is distributed to 'the s ark plu 10 by means of a distributor 12.

he distrlbutor 12 shown has a distributing arm 14, which is maintained in permanent connection with the secondary winding of the coil 5 by means of a 'slip ring conne'ction 15 and distributes the ignition current by rotation past and into successive c0- operation with the contacts 16, to which the spark plugs 10 are individually connected by means of leads 18.

The end of the distributing arm 14 preferably contacts directly with the contacts 16 successively in its rotation, but it is to be understood that the successive cooperation of the arm 14 with the contacts 16 may be through relatively small gaps to avoid unsatisfactory contact through carbonization or otherwise, after use. The distributor 12, aswell as the interrupter 8 may be operated from the timing gears of the en- A gine in the usual or any preferred manner,

as well understood in the art.

The circuit, as thus far described, is merely illustrative .for the purpose of acquainting those skilled in the art with one embodiment of the present invention. This circuit may constitute any suitable or preferred ignition system and may vary, as desired. The impedances 20 and 21l correspond to the impedances 20 and 21 of Figure 1 of my copending application, Serial No. 365,934, filed May 25, 1929, and are provided for plug and circuit testing purposes, in accordance with the disclosure of that application.- A suitable switch arm 22, pivoted at 23, is adapted l for selectively completing either of the parallel or shunt i214npedances 20 or 21 to a ground connection For the purposes of the present application, suiice it to say that the impedance 20 may ybe of relatively low ohmic resistance, say of the order of 125,000 ohms, or of such a value that, when applied in shunt or parallel to the ignition system by means of the switch 23, theurrent dow to a normally or satisfactory operating plug will be shunted wholly or partially through the impedance to ground 24. This entire or partial shunting of the current through the impedance 20, as the distributor arm 14 moves successively into cooperation with the plug contacts 16, will either extinguish or reduce the illumination of the gaseous tube indicator 26 and the extinguishment or reduction in illumination of the indicator 26 will indicate that the plug 10, which is connected through the indicator 26, when l-the Aextnguishment or reduction in illumination occurs, is operating satisfactorily, or at least will indicate the condtion of the AFor example, if suiiicient carbonization has occurred at the contacts of the particular plug 10 to lower the impedance at the jump gap of the plug below the desired standard, the tube 26 will be illuminated relatively brightly when the impedance 20 is applied. This relatively bright illumination of the tube 26 will indicate that the particular plug 10 connected'therewith is defective, or at least not in normal operating condition.

The other impedance 21 may be in the form of a suitable resistance or other potential limiting device. It might even be a potential limiting gap, but in the illustrated embodiment isV shown in the form of a resistance, say, for example, a 250,000 ohm resistance, or a resistance ,or other limiting beyond the value of the impedence 21,

which impedance 21 thereupon forms a limiting device for preventing breaking down of the entire system. At the same time, when the gap 29 at any particular plug 10 is increased beyond the value of the im` pedance 21, the current flow will be shunted entirely by the impedance 21 and with the insulation of the ignition system and particularly the leads 18 in proper or suitable condition, the bulb 26 will be substantially extinguished.

If there are objectionable stray or leakage paths, for example, in the insulation of the leads 18, the current will continue to ilow through the tube 26, when the gap 29 is thus increased, and the continued illumination of the bulb 26 will indicate that the insulation tothe particular plug 10 is not satisfactory. At the same time,-due to the sensitive character of the Neon or other gaseous tube 26 and the ability of said tube 26 to show or reflect the slightest differences in current passed therethrough, the particular resistance or amount of leakage in any plug circuit may be ascertained by inspection of the action of the tube 26. If, for example, with the plug gap 29 increased beyond the impedance 21, the bulb 26 burns at relatively great brilliancy when the circuit to that plug isl completed, this lwill indicate that the leakage in that circuit is of 'relatve- 1y great magnitude, whereas, if the'tube 26- continues to burn, but at lower brilliancy, this will indicate that there is a leakage path of less magnitude.

In Figures 1 and 2, the distributing arm 14 is shown as comprising a thin, metallic strip, having the contact making-end 30 ofi"- set downwardly at 31 and provided, at its opposite end, with integral clip forming tongues 32, which are turned up and suit-- ably formed to yieldingly receive, as well as hold and contact with, the plug 34 of the Neon or other gaseous tube 26. The tube 26 is, in this case, preferably a low resistance "Neon or other gaseous tube and the threaded contact shell 34 of the tube is connected with the arm 30 by its contact with the sides of the clip portion 32 and the other side of the tube 26 is connected with the contact 35, which, in turn, contacts with the contact 36 of the slip ring 37, which cooperates or 'contacts with the slip ring brush 15 (Figure 1). A

The tube 26 preferably has a pair of electrodes 26a, one connected with the contact shell 34 andthe other connected with the contact 35. The gaseous 'content of the tube forms thegconnecting path between the electrodes internally of the tube.

In the embodiment of Figures 1 and 2, the arm 14 is secured bymeans of a screw 38 to the post 39, which constitutes the usual or any preferred distributor post well known in the art and the slip ring 37 embraces this post and is suitably securedthereon. It is to be understood that, in this form of the invention, the gaseous tube 26 rotates with the distributor arm 14 and is thereby applied successively to the plug leads-18 in the particular order of timing of the engine. As already pointed out, with the impedance paths 20 and 21 eliminated, the gaseous tube itself will give a valuable indication of the actual functioning of the icnition system..

The slip ring 37 is preerably provided with a contact finger 40 turned up with a gap at 41, across which the current is adapted to jump to complete the circuit to the plug across this gap` 41 in the event the tube 26 is burned out or fails. This prevents the possibility of failure of the current supply to the plugs 10, in case the gaseous tube 26 burns out, or otherwise fails.

In the embodiment of Figure 3, the engine plugs 10' are connected through leads 18',

with thecontacts 16 and the contact arm 14 rotates successively into contact or cooperation with the contacts 16', as before.

The circuit to the distributor arm 14' is not shown beyond the slip ring 37 and cooperating brush 15 contacts. In this case, the Neon or other gaseous tube 26', instead of being disposed :directly in the distributor arm for rotation therewith, as be. fore, is adapted for stationary positioning away from the distributor, as, Jfor example, upon A.tzhedash of the vehicle', `or otherwise, as desired/... A single tube 26 is shown for all of. th'plugs 1 0' of the'engine, but it is `to be understood that separate Neon or other gaseous tubes might be provided in thev several plug circuits 18'. A conducting wire 45 is grounded at- 46 and is provided with a plurality of leads 47, which I find need only be wrapped around the external Surface of the tube 26, as indicated at 48. Conducting leads 49, one wrapped at 5() externally around the tube 26 between each of the respective pairs vof leads 47 are connected with the respective plug leads 18. The leads 49 may either be given metallic contact with the plug leads 18 or or preferably need only be given a wrap around the insulation of cables forming the leads 18', forming in effect inductive or condenser connections therebetween. When a spark impulse occurs, for example, in the particular plug 10 shown in Figure 3, the dis` charge within the tube 26' will occur between the wrapped end 50"()71 the v49 rextending from the connection 18 to that plug and the wrapped ends 48 of the ground leads 47 onopposite sides of the lead 49. Similarly, the discharge within the tube 26 for plug 6 will occur between the lead49 for that plug and the wrapped ends of the ground leads on opposite sides of that lead. The ground wire may extend internally through the tube.

Considering the distributor arm 14 as rotating in a clockwise direction in Figure 3, the usual firing order Iisdesignated by appropriate markings in that figure.

In the embodiment of Figures 4 to 8, the entire indicating system of the present invention is carried by a cover 55, which may be of suitable insulating material and possibly adapted to be substituted for the usual distributor cover now employed. The cover has the usual depending flange 56, forming the space 57 within which the distributor arm 58 rotates. The arm 58 is the usual or any preferred distributor arm and the cover 55 is provided with upstanding hollow bosses 59, carrying contacts 60, one of which is connected with each of the engine plugs by means of a lead 61. The arm 58 usually has a spring` contact element 62, which rotates with the arm 58 into successive contact with the contacts 60 to distribute the current to the plugs in the usual manner.

Integral with the top of the cover 55 is an upstanding hollow post 63, which may be internally reduced and internally threaded at its upper end at 64 to receive a terminal nut 65, which is metallic and has a socket 66 in which thev bared end of the lead 67 from the spark coil is secured mechanically and in good electrical contact with the nut for supplying to the distributor the high potential ignition current for the spark plugs. The lower end of the nut 65 is reduced and externally threaded at 68 to receive an insulating sleeve 69, which may be of fiber, Bakelite, or the like. A metallic post 70, having a reduced an`d externally threaded up er end threaded into the lower end of the s eeve 69, as indicated at 71, extends downwardly and has a constant elec- .trical contact, as by means of a spring brush contact 72 with pressed or yieldable the contact the distributor arm 58, or with 62 thereof.

The Neon or other gaseous tube is indicated at 73 and 1s again, preferably, a relatively low resista-nce gaseous tube, although this may vary. This tube 73 is mounted within the sleeve 69, with one end in contact witha reduced integral extension 74 of the post 7 0, or with a metallic spacer or connecting element therebetween. For the purpose of holding the tube against rattling or vibration within the sleeve 69 and to provide good electrical connection between the terminal nut 65 and the oppol site end of the tube, a coiled spring 75 is interposed between the inner reduced end l contact, at all times. From the 4foregoing,

it will now be apparent that every time that the distributor arm 58 or contact 62 thereof vcontacts with one of the contacts 60, a circuitis completed through the gaseous tube 73 and the action of the tube 73 will indicate the condition of the particular plug, plug circuit or other factor reflected in the current flow through the tube 73. The tube 73 is preferably provided with electrodes 73 and 73h.

For the purpose of cyclically exposing the light and indicating which plu plug circuit or other condition reilecte -therein is indicated, an upright sleeve 78 is provided concentrically within the hollow post 63 and around the sleeve 69. The sleeve 69, which has relatively fixed position in o ration,

that is, it need not rotate, is provi ed with an elongated sight opening 7 9. The sleeve 78 is flanged and secured at its lower end at 80 to rotate with the arm 58 and within the vertical length of the sklight opening 79, the sleeve 78 is provided with a plurality of individual sight openings 81.

The openings 81 are equal'in number to the number ot engine pl or plu circuits, or other conditions w 'c it is esired to indicate, and these openin s 81 are equally spaced helically around t e sleeve 78, as shown in Figure 6. The openings 81 are, preferably, in the form of numbers cor-r responding with the respective spark lug circuits indicated thereby, as indicate in Figure 6, but this may be varied by using ordinary openings, as indicated in Figure 4',` in which case the post 63 may be calibrated as indicated more or less diagrammatically at in Figure 4. In o ration, the Neon or other gaseous tu 73 is lighted as the distributor arm or contact 72 contacts successivelyeach of the contacts 60 and the sight openings 81, as they pass the vertically elongated sight opening 79 and the registering vertically elongated sight opening 82 in the tubular post 69 will cyclically indicate, by the action of the lug, the condition which it is desired to etermine. The position vertically of the o ning 81 will indicate which plug or wliiech plug circuit it is, the condition of which is 7 indicated. For example, as the upper opening 81 (Figure 6) passes the registerin sight openings 79 and 82, the relatively hig position of the indication will indicate that the indication is for plug No. 1 or plug ciri Vio cuit No. 1. VAs the lower opening 81 passes the openings 79 and 82, the low position of the indication will indicate that the indication is for plug or plug circuit No. 4 and the relative vertical positions of the indications therebetween will indicate the particular plug or plug circuit which Ais indicated. Where the openings 81 are in the form of numbers, as shown in Figure 6, the vertical position ofl the indication is not so important. f In Figure 8, the sleeve 69 is shown as being provided with conductor means 86 and 87 connected respectively with the terminal nut 65 and post 70 and separated at 88 to form a small gap across which the plug circuits are completed in the event the tube or lamp 73 is burned out or fails.

Where the impedances 20 and 21 of the form of the invention illustrated in Figure 1 are employed, these may be housed within a suitable insulating box 89, which may be attached directly to the cap 55, as indicated more or lessdiagrammatically in Figure 4. For applying these impedance paths selectively in shunt to the ignition system; each impedance may have a contact 90 extending ,upwardly from the box 89 and the head of the terminal nut 65 may be provided with a contact finger 91, adapted to be engaged with either of the contacts 90 by rotation of the nut 65 within the upper end of the post 63. It is to be understood that the indicating means illustrated in Figures 4 to 8 may be mounted upon the dash of the vehicle or otherwise, as desired, and' connected either direct or through phantpm circuits with the ignition system. The indicating sleeve 78 may be driven synchronously with the distributor arm, either mechanically or electrically, or otherwise.

. Either system may be used with the ground or parallel shunt provision independently' connected, or without these provisions.

In the embodiment -illustrated in Figures 9 to 11, the distributor post 63 may be of substantially standard or any suitable or preferred form, with the central connection at 200 to the distributor arm 58. The arm 58 has a contact spring 98 for contact with the terminals 99, which are, in turn, connected by leads 100 'with the respective spark plugs of the engine.

The top 95 of the distributor cap 55 is provided with a plurality of sight openings 96, one for each of the engine plugs or plug circuits and disposedv alternately between the hollow plug .contact bosses 59. The openings 96 may be provided with suitable panes 97, as indicated in Figure 11 and the -distributor arm 58 ca-rries a Neon or other suitable gaseous tube 102, which is successively connected in. the circuit from the center supply connection to the respective spark plug circuits, as the distributor arm successively contacts the terminals 99. When the distributor arm is in contact with the particular terminal 99, as shown, for example, the tube 102'is positioned beneath the opening 96 corresponding with that terminal 99 and the spark plug circuit connected therewith and a positional indication is given thru the opening 96. The sight tributor terminals 107 are connected with the respective engine plugs and the spool contacts 108 are cooperable with the brushes 109 connected with the terminals 107 for successively completing the circuits to the respective plugs. This embodiment is particularly adapted for application to a high tension magneto system. The tube 110 of this form preferably has electrodes 1103.

The Neon or other gaseous tube or indicating lamp 110 is successively connected between the current supply conductor 111 and the distributor terminals 107 and is preferably carried by the spool 105 for rotation therewith past sight openings or apertures 115. The central terminal is indicated more or less diagrammatically at 112 and the circumferentially spaced sight openings corresponding with the respective spark plug circuits for positional indication, as in the previous embodiment may be provided thru .the front of the enclosure 106 and may be covered with glass or other suitable transparent windows thru Which the tube 110 may be visible or the light emitted for positionally indicating the condition of the spark plug circuits. The showing of this form of the invention is diagrammatic, but Iis believed suii'icient for acquainting those skilled in the art with this form of positional indication. The spool 105 and enclosure 106 may be provided .with cooperating contacts for selectively applying the shunt impedances 20 and 21 of Figure 1 by relative movement between the spool 105 and the case or enclosure 106.

Thisrelative movement may be either relative rotational movement or relative axial movement, contacts being preferably arranged to complete a circuit through the tube 110 first, so that it may be determined through the opening 116 whether the tube 110 is functioning and thereafter the rela- 'tive movement between the spool and case bringing contacts into cooperation for applying the relatively high impedance to the ignition circuit, whereupon the tube 110 will be extinguished or diminished in action, where the system is functioning normally or suitably.

In Figure 14, I have shown an independent gaseoustube 125 for eachspark plug 126. In this case,.I have shown the individual tube as connected between the plug and the lead 127 thereto and as being supported directly upon the plug. The tube 125 may be properly protected against mechanical injury, as by means of a metal lantern 128 having sight openings 129 and the tube 125 may be provided with suitable terminal connections 130 and 131 for connecting it between the high tension lead or cable 127 and the plug electrode. Each tube 125 will light as the corresponding plug fires and will indicate the functioning and condition of the particular plug with which it is associated and the ground shunt tester is preferably used in combination with this system. f

In the embodiment of Figure 15, the gaseous or indicating tube is indicated at 140 and a reflector therefor is indicated at 132. The distributor cover is indicated at'133 and is provided with contact-terminals 134'connected by leads 135 with the spark plugs.

- The rotatabledistributor arm is indicated at' 136 and the bulb 130 is provided with a lantern case 137 provided with sight openings 138, through which the il lumination or light produced by the tube 130 is viewed. The central ignition wire to the distributor arm, indicated at 140, is connected with the terminals 141 and 142 of the tube 130 and this wire may be connected to a ground shunt through a lead 143. The distributor arm 136 is provided with a permanent magnet 145, which rotates therewith and a compass needle is provided at 146. In this case, the compass needle is rotated by the magnetic influence of the magnet 145 on the distributor arm and turns .therewith in the rotation of the distributor arm and the illumination from the bulb 130 shows the position of the compass needle at each ignition point, thereby providing a positional indication, the colnpass needle preferably being a mirrored or reflecting needle for reflecting the illumination from the lamp. As an alternative, the needle 146 may be driven mechanically, or otherwise,

' by the distributor arm. This scheme for illuminating the rotating needle or arm from the bulb 130 in the ignition circuit may be carried out on the instrument board by means of a small motor (synchronous) driven from the synchronous generator on the cam shaft or distributor shaft.

In Figure 16, a hi h resistance circuit, indicated diagrammatically at 150, is located preferably` inside of the tube 151 and is placed in parallel with the gaseous path circuit through the tube and in electrical or electrostatic relation thereto. terminals are indicated at 152 and 153 and the parallel high resistance 150 may be connected with one of these terminals as, for example, the terminal 153, as shown.

With such an arrangement, a relatively strong charge will follow the high resistance ath 150 and will also follow the Neon or gaseous path through the entire length of the tube, whereas a weak, or relatively weak, charge will follow the high resistance path and will also follow the aseous path, but only part way the lengt of the tube. `The gas discharge will travel from the terminal 152 to diii'erent points, 1 or example, 155, 156, 157, 158, 159, 160, along the high resistance path 150, depending upon the strength of the charge. This arrange- 'ment provides for weighing or measuring the strength of the charge through the tube and, in view of the extreme sensitiveness `of the tube 151, ve slight variations may be ascertained relatlvely. The high resistance path 150 may be calibrated, as at 155 to 160. The device of 116 is in the nature of a `volt meter.

In Figure 17, I have shown individual Neon or other suitable gaseous tubes 190 arranged at the distributor with one tube 19()v connected between each of the individual spark plug connections or leads 191 and the stationar circumferentially spaced contacts 192 of t e distributor. The rotating dis- V tributor arm is indicated at 193 and the center lead or circuit connection thereto is indicated at 194.

In Figure 18, a. single Neon or other gaseous tube 230 is mounted upon the dash 232 of a motor vehicle and connected into the ignition circuit 234 leading to the distributor (not shown). A grounding or test circult connection may be applied to the circuit 234 ahead of the vtube 230, as indicated at 235, and this grounding or test circuit connection means may also be mounted upon the dash 232 of the vehicle. The single tube 230 serves, in this case, as a common indi- .cater for all of the spark plug lines of the ignition system.

any of the cases herein described, the iirmg or ignition point in the cycle of the internal combustion engine may be indicated by the angular position of the gaseous bulb at the time of lightin shape of the gaseous bulb and the related density of gaseous illuminosity may 'be used for comparative determinations of current density. .Variations in the size, sha e and relative positionment of the electro es, in connection with'the relative location and intensity of gaseous illumination may also be used for comparative determinations of current density.

The tube Variations in thev I do not intend to be limited to the precise details shown or described.

I claim: j

1. In combination, an ignition System, a source of current for said system, a plurality of ignition circuits leading from said system and having ignition devices therein, means for distributing the current to said ignition devices, indicating means including a gaseous tube connected with said system and adapted for individually indicating the condition of said. ignition circuits, and means operable synchronously with the distributor for changing the position of indication for the respective circuits, said means comprising a rotating shield having helically arranged openings.

2. In combination, an ignition system, a source of current for said system, a plurality of ignition circuits leading from said systemvand having ignition devices therein, means for distributing the current to said ignition devices, indicating means including a gaseous tube connected with said system ,and adapted forindividually indicating the condition of said ignition circuits, means operable synchronously With the distributor for changing the position of indication for the respective circuits, said means comprising an enclosure having spaced "openings therethrough, and a mirrored member operated synchronously With the distributor for reflecting the illumination through the opening corresponding with the ignition circuit. 4

3. In combination, an ignition system, a source of current for said system, a plurality of ignition circuits leading from said system and having ignition devices therein, means for distributing the current to said ignition devices, said means including a rotatable distributor arm and indicating means comprising an electric lamp lnounted on said arm and connected into said system through said arm for indicating the condition o said ignition circuits.

4. In combination, an ignition system` a source of current for said system, a plurality of ignition circuits leading from said system and having ignition devices therein, means for distributing the current to said ignition devices, said means including a rotatable distributor larm having a distributor case, a cover for said case, a tubular extension on said cover, and indicating means comprising an electric lamp mounted in said extension and having a contact contacting with said arm for connection in the svstem therethrough to indicate the condition of said ignition circuits.

5. In combination, an ignition system, a source of current for said system` a plurality of ignition circuits leading from said system and having ignition devices therein, means for distributing the current to said with said distributor arm, said shield having openings in different positions, one for each of said ignition circuits for exposing the indication of said lamps positionally.

source of current for said system, a plurality of 1gn1t1on lc1rcu1ts leadmg from sald system and havlng ignitlon devices therein,

6. In combination, an ignition system, a

means for distributing the current to said ignition devices, said means includ? ing a rotatable distributor arm and a distributor case, a cover for said case, a tubular'extension on said cover, indicating means comprising an electric lamp mounted in said extension and having a contact contacting with said arm for' connection in the system therethrough to indicate the vcondition of said ignition circuits, said tubular extension having a sight opening, a shield surround. ing said lamp and driven synchronously with said distributor arm, said shield having openings in different positions, one for each of said ignition-circuits for exposing the indication of said lamps positionally, and a holder for said lamps mounted Within said shieldl and having a sight opening registering with the sight opening in said tubular extension.

7. In combination, an ignition system.V a source of current for said system, a plurality of ignition circuits leading from said system and having ignition devices therein, means", for distributing the current to said lignition devices, said means including a rotatable distributor arm and a distributor case, a cover for said case, a tubular extension on said cover, indicating means comprising an electric lamp mounted in said extension and having a contact contacting with said arm for connection in the system therethrough to indicate the condition of said ignition circuits, said tubular extension having a sight opening, a shield surrounding said lamp and driven synchronously with said distributor arm, said shield having openings in dilierent positions, one for each of said ignition circuits for exposing theA indication of said lamp positionally, a holder for said lamp mounted Withinsaid shield and having a sight opening registering with the sight opening in said tubular extension, and a shunt path in said lamp holder of greater impedance than the lamp and connected around devices, said means including a rotatable distrlbutor arm and a dlstrlbutor case, a coverl for said case, a tubular extension on said cover, indicating means comprising an elecf tric lamp mounted in said extension and having a contact contacting with said arm for connection in indicate the condition ofsaid ignition circuits, an impedance box mounted upon said cover and having contact means and a Atermmal nut for the lamp mounted upon said cover and having cooperating contact means movable into and out of contact with' said first contact means by adjustment yof said .I nut.

v comprisin 9. In combination, an ignition system, a source of current for said system, a plurality of ignition circuits leading from said system and having ignition devices therein,

means for distributing the current to saidignition devices, said means including a rotatable distributor arm, indicating means an electric lamp mounted adjacent sai arm and connected into said system through condition of said ignition circuits, a distributor having a distributor case, a distributor arm rotatable within said case, and

means carried by said case and enclosing said lamp, said means having a. plurality of sight o enings in different positions and one for eac of said ignition circuits.

10. In combination, an ignition system, a.

source of current for said system, a plurality of ignition circuits leading from said system and having ignition devices therein, means for distributing the current to said ignition devices, said means including a rotatable distributor arm, indicating means comprising an electric lamp mounted adjacent said arm and connected into said system through said arm for indicating the con dition of said ignition circuits, aX distribu tor having a distributor case, means carried by said case and enclosing said lamp, said means having a plurality of sight openings in diil'erent positions and one for each of said ignition circuits, and a mirrored member rotatable synchronously with the distributor arm and adjacent said openings for positionally reflectingthe illumination of said lamp therethrou h.

In witness whereo I hereunto subscribe my naine, this 22nd da of May, 1929.

' HER N C. HEATON.

the system therethrough to saidV arm for indicating the 

